Frequency of discontinuation of injectable osteoporosis therapies in US patients over 2 years

Abstract

Little is known about treatment patterns with injectable osteoporosis therapies. At 12 months, the probability of discontinuation was 69.1% among patients using ibandronate, followed by teriparatide (67.1%), zoledronic acid (59.2%), and denosumab (48.8%). By 24 months, discontinuation was higher for each treatment. The majority of US patients discontinue injectable osteoporosis treatment by the end of the first year following initiation.

Introduction: This study was designed to assess the frequency of treatment discontinuation over time among patients who initiate injectable osteoporosis therapies.

Methods: This retrospective observational study utilized an administrative claims database to measure discontinuation of injectable osteoporosis therapy, reported at 6-month intervals over 2 years. Eligible patients were aged ≥55 years, had newly initiated injectable osteoporosis therapy between January 2008 and June 2012, and were continuously enrolled in the health plan for ≥1 year prior to and ≥1.5 years after the date the first injectable medication was received (the index date). Follow-up time ranged from 18 to 24 months. Injectable osteoporosis treatments included in the analysis were denosumab, ibandronate, teriparatide, and zoledronic acid. Discontinuation was assessed using Kaplan-Meier survival analysis and was defined at each time point as the percentage of patients who did not receive the dose scheduled for that time point. A 90-day grace period was allowed to accommodate flexibility in the scheduling of post-index re-administrations. Sensitivity analyses assessed discontinuation using grace periods of 60 and 30 days.

Results: A total of 4756 patients met the inclusion criteria for the study, with 617 utilizing denosumab, 233 ibandronate, 778 teriparatide, and 3128 zoledronic acid. At 12 months, discontinuation was highest among patients using ibandronate (69.1%), followed by teriparatide (67.1%), zoledronic acid (59.2%), and denosumab (48.8%). By 24 months, discontinuation was higher for each treatment: 87.5% for ibandronate, 87.9% for teriparatide, 79.8% for zoledronic acid, and 64.3% for denosumab.

Conclusions: The majority of US patients discontinue injectable osteoporosis treatment by the end of the first year following initiation.

Keywords: Discontinuation; Drug therapy; Injections; Medication adherence; Osteoporosis; Patient compliance; Postmenopausal; Subcutaneous.